Hang over the gents' mophead (4)
I believe the answer is:
loom
'hang over' is the definition.
(I've seen this before)
'gents' mophead' is the wordplay.
'gents'' becomes 'loo' (gents toilet).
'mophead' becomes 'm' (head letter of 'mop').
'loo'+'m'='LOOM'
'the' is the link.
(Other definitions for loom that I've seen before include "Weaving machine to appear indistinctly" , "Apparatus for weaving cloth" , "weaver" , "Bulk large" , "See 12" .)